GFCI with Capacitive Power Supply Circuit

ABSTRACT

A ground fault circuit interrupter (GFCI), with Capacitive Power Supply Circuit, for interrupting the flow of current through a pair of lines extending between a source of power and a load when a around fault condition is detected.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is related to, claims the earliest availableeffective filing date(s) from (e.g., claims earliest available prioritydates for other than provisional patent applications; claims benefitsunder 35 USC § 119(e) for provisional patent applications), andincorporates by reference in its entirety all subject matter of thefollowing listed application(s) (the “Related Applications”) to theextent such subject matter is not inconsistent herewith; the presentapplication also claims the earliest available effective filing date(s)from, and also incorporates by reference in its entirety all subjectmatter of any and all parent, grandparent, great-grandparent, etc.applications of the Related Application(s) to the extent such subjectmatter is not inconsistent herewith:1. United States provisional patent application 62/519322, entitled “AGround Fault Circuit Interrupter (GFCI) with Capacitive Power SupplyCircuit”, naming Victor Aromin as inventor, filed 14 Jun. 2017.

FIELD OF USE

The present invention relates generally to electrical safety devices andmore particularly to ground fault circuit interrupters (GFCI).

DESCRIPTION OF PRIOR ART (BACKGROUND)

Conventional electrical appliances typically receive alternating current(AC) power from a power supply, such as an electrical outlet, through apair of conducting lines. The pair of conducting lines, often referredto as the line and neutral conductors, enable the electrical appliance,or load, to receive the current necessary to operate.

The connection of an electrical appliance to a power supply by a pair ofconducting lines creates a number of potentially dangerous conditions.In particular, there exists the risk of ground fault and groundedneutral conditions in the conducting lines. A ground fault conditionoccurs when there is an imbalance between the currents flowing in theline and neutral conductors. A grounded neutral condition occurs whenthe neutral conductor is grounded at the load. A ground fault conditionis extremely dangerous, and can result in serious injury.

Ground fault interrupters include ground fault circuit breakers, groundfault receptacles, and even cord mounted ground fault protectiondevices. Ground fault interrupters may be troubled by false tripping,even though they pass all present industry standards. One cause of falsetripping, is disconnection of the power to inductive appliances,particularly by unplugging the appliances.

Examples of these appliances include electric shavers, high intensitylamps, and small cooling fans, such as are used for cooling electronicequipment. Unplugging these appliances generates an arc between the plugand the receptacle, resulting in the superimposition of several volts ofwide band noise onto the power line. Due to the wide band nature of thenoise, even a very small stray coupling capacitance will couple thenoise from the power line conductor into the ground fault circuit,causing a false trip.

A typical ground fault interrupter includes an operational amplifierwhich amplifies the sensed ground fault signal and applies the amplifiedsignal to a window comparator which compares it to positive and negativereference signals. If either reference value is exceeded, a trip signalis generated. A common type of ground fault detection circuit is thedormant oscillator detector. This detector includes a first sensor coilthrough which the line and neutral conductors of the protected circuitpass. The output of the first sensor coil is applied through a couplingcapacitor to the above-described operational amplifier followed by awindow comparator. A line-to-ground fault causes the amplified signal toexceed the reference value and generates a trip signal.

The dormant oscillator ground fault detector includes a second sensorcoil through which only the neutral conductor passes. Aneutral-to-ground fault couples the two detector coils causing theamplifier to oscillate which also results in generation of a tripsignal.

It has been found that wide band noise induced by load related switchingphenomena such as is caused by unplugging, inductive appliances causesfalse tripping of the ground fault interrupter.

Ground fault circuit interrupters are well known in the art and arecommonly used to protect against ground fault and grounded neutralconditions. In general, GFCI devices sense the presence of ground faultand grounded neutral conditions in the conducting lines and in responsethereto, open at least one of the conducting lines between the powersupply and the load to eliminate the dangerous condition.

In U.S. Pat. No. 5,177,657, to M. Baer et al, there is disclosed aground fault interrupter circuit which interrupts the flow of current toa pair of lines extending between a source of power and a load. Theground fault interrupter circuit includes a circuit breaker comprising anormally open switch located in one or both of the lines, a relaycircuit for selectively closing the normally open switch, an electroniclatch circuit operable in first and second bi-stable states and a faultsensing circuit for sensing the presence of a fault condition in atleast one of the lines. The electronic latch circuit causes the relaycircuit to close the normally open switch and maintain the normally openswitch in its closed position when the electronic latch circuit is inthe first bi-stable state. The electronic latch circuit also causes therelay circuit to permit the normally open switch to return to itsnormally open condition when the latch circuit is in its secondbi-stable state. A fault sensing circuit senses the presence of a faultcondition in at least one of the lines and causes the electronic latchto latch in its second state upon detection of the fault condition.

In U.S. Pat. No. 5,418,678 to T. M. McDonald, there is disclosed animproved ground fault circuit interrupter (GFCI) device which requiresmanual setting following initial connection to an AC power source ortermination of a power source interruption. The improved GFCI deviceutilizes a controlled switching device which is responsive to a loadpower signal for allowing the relay contact sets of the GFCI device tobe closed only when power is being made available at the output or loadterminals. The controlled switching device preferably comprises anopto-isolator or other type of switching device which provides isolationbetween the GFCI input and output terminals when the relay contact setsare open. The improved GFCI device may be incorporated into portableunits, such as plug-in or line cord units, for use with unprotected ACreceptacles.

In U.S. Pat. No. 4,816,957 to L. F. Irwin there is disclosed an adapterunit comprising a moisture resistant housing within which is carried animproved, self-testing ground line fault interrupter device. Theimproved device is electrically interconnected with a connector carriedexternally of the adapter housing so that the unit can be pluggeddirectly into a standard duplex outlet of an existing circuit. Theapparatus includes circuitry that automatically tests the operability ofthe device when it is plugged into a duplex outlet without the need formanual manipulation of test buttons or other overt action by the user.

In U.S. Pat. No. 4,578,732 to C. W. Draper et al there is disclosed awall socket type ground fault circuit interrupter having a pair ofsockets, a reset button and a test button that are accessible from thefront of the interrupter. The interrupter has latched snap-actingcontacts and a novel latching relay structure for maintaining thesnap-acting contacts in a circuit making position. The snap-actingcontacts permit all of the components including the monitoring toroidsand the power supply to be respectively located and connected at theload side of the snap-acting contacts so that all of the circuits of theinterrupter are de-energized when the contacts snap to a circuit openingposition. The snap-acting contact mechanism and relay are provided withstructures which provide the interrupter with a trip-free mode ofcontact actuation and accordingly a tease-proof snap-acting contactoperation.

One drawback of GFCI devices of the type described above is that theGFCI device generally includes a large solenoid to selectively open andclose the switching device. Specifically, the solenoid generallyrequires a constant supply of line voltage (approximately 120 volts) inorder to switch and sustain the solenoid in its energized state. As aconsequence, the solenoid acts as a large power drain source.

Thus, there is a need for a solenoid of sufficient rating for use in aline voltage GFCI device but with reduced tendency to fail due to highvoltages and currents associated with typical line voltages.

There is also a need for a ground fault interrupter which does notgenerate a false trip in response to wide band noise in the protectedcircuit.

There is also a need for such a ground fault circuit with improvedimmunity to wide band noise which also responds to sputtering arcfaults.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a new and improvedground fault circuit interrupter (GFCI).

It is another object of the present invention to provide a GFCI whichsenses the presence of ground fault and grounded neutral conditions inthe conducting lines, and in response thereto, includes a solenoid whichopens at least one of the conducting lines between the power supply andthe load.

It is yet another object of the present invention to provide a GFCI ofthe type described above wherein the solenoid can be energized andsustained in the energized state with minimal power drain.

It is still another object of the present invention to provide a GFCI ofthe type described above wherein the solenoid can be energized andsustained in the energized state with minimal heat build-up.

It is a further object of the present invention to provide a GFCI of thetype described above which may be mass produced, has a minimal number ofparts, and can be easily assembled.

A GFCI constructed according to this invention for interrupting the flowof current through a pair of lines extending between a source of powerand a load comprises a circuit breaker having a switch located in one ofsaid lines, said switch having a first position in which the source ofpower in its associated line is not connected to the load and a secondposition in which the source of power in its associated line isconnected to the load, a relay circuit for selectively moving andmaintaining said switch in either said first position or said secondposition, said relay circuit including a solenoid operable in either anenergized state or a de-energized state, said solenoid setting saidswitch in said second position when in its energized state and settingsaid switch in said first position when in its de-energized state, abooster circuit for selectively supplying a first voltage to thesolenoid sufficient to cause said solenoid to switch from itsde-energized state to its energized state, said first voltage beingsupplied to said solenoid through said switch when said switch is in itsfirst position, a power supply circuit, said power supply circuitsupplying a second voltage to the solenoid, said second voltage beingsufficient to maintain the solenoid in its energized state after beinginitially energized by the first voltage, the second voltage being lessthan the first voltage, the second voltage being insufficient to switchsaid solenoid from its de-energized state to its energized state, alatch circuit operable in first and second bi-stable states, said latchcircuit allowing said solenoid to switch from its de-energized state toits energized state and remain in its energized state when in said firstbi-stable state and causing said solenoid to switch from its energizedstate to its de-energized state and remain in its de-energized statewhen in said second bi-stable state, and a fault detecting circuit fordetecting the presence of a fault condition in at least one of saidlines extending between the power and the load and for causing saidlatch circuit to latch in its second bi-stable state upon detection ofsaid fault condition. In addition the circuit contains a fault detectingcircuit for detecting the presence of a fault condition in at least oneof said lines extending between the power and the load and for causingsaid latch circuit to latch in its second bi-stable state upon detectionof said fault condition. The fault detecting circuit comprises a 26VZener shunt regulator, an OP amp, and a SCR driver; and at least onepassive RF noise suppressor for preventing RF noise from being amplifiedby the OP amp and inadvertently triggering the SCR driver. The circuitalso includes a light emitting diode circuit for indicating the GFCI isoperating normally.

Another GFCI constructed according to this invention for interruptingthe flow of current through a pair of lines extending between a sourceof power and a load comprises a circuit breaker having a switch locatedin one of said lines, said switch having a first position in which thesource of power in its associated line is not connected to the load anda second position in which the source of power in its associated line isconnected to the load, a relay circuit for selectively moving andmaintaining said switch in either said first position or said secondposition, said relay circuit including a solenoid operable in either anenergized state or a de energized state and means coupled to saidsolenoid for controlling the state of said solenoid, said solenoidsetting said switch in said second position when in its energized stateand setting said switch in said first position when in its de-energizedstate, a booster circuit for selectively supplying a first voltage tothe solenoid sufficient to cause said solenoid to switch from itsde-energized state to its energized state, said first voltage beingsupplied to said solenoid through said switch when said switch is in itsfirst position, a power supply circuit, said power supply circuitsupplying a second voltage to the solenoid, said second voltage beingsufficient to maintain the solenoid in its energized state after beinginitially energized by the first voltage, the second voltage being lessthan the first voltage, the second voltage being insufficient to switchsaid solenoid from its de-energized state to its energized state, and afault detecting circuit for detecting the presence of a fault conditionin at least one of said lines extending between the power and the loadand for causing said latch circuit to latch in its second bi-stablestate upon detection of said fault condition.

Another GFCI constructed according to this invention for interruptingthe flow of current through a pair of lines extending between a sourceof power and a load comprises a circuit breaker having a switch locatedin one of said lines, said switch having a first position in which thesource of power in its associated line is not connected to the load anda second position in which the source of power in its associated line isconnected to the load, a relay circuit for selectively moving andmaintaining said switch in either said first position or said secondposition, said relay circuit including a solenoid operable in either anenergized state or a de energized state, said solenoid setting saidswitch in said second position when in its energized state and settingsaid switch in said first position when in its de-energized state, apower supply circuit for supplying power to said GFCI, a latch circuitoperable in first and second bi-stable states, said latch circuitallowing said solenoid to switch from its de-energized state to itsenergized state and remain in its energized state when in said firstbi-stable state and said latch circuit causing said solenoid to switchfrom its energized state to its de-energized state and remain in itsde-energized state when in said second bi-stable state, a faultdetecting circuit for detecting the presence of a fault condition in atleast one of said lines extending between the power and the load and forcausing said latch circuit to latch in its second bi-stable state upondetection of said fault condition, and a trip indicating circuit forindicating that said fault detecting circuit has detected a faultcondition.

Another GFCI constructed according to this invention for interruptingthe flow of current through a pair of lines extending between a sourceof power and a load comprises a circuit breaker having a switch locatedin one of said lines said switch having a first position in which thesource of power in its associated line is not connected to the load anda second position in which the source of power in its associated line isconnected to the load, a relay circuit for selectively moving andmaintaining said switch in either said first position or said secondposition, said relay circuit including a solenoid operable in either anenergized state or a de energized state, said solenoid setting saidswitch in said second position when in its energized state and settingsaid switch in said first position when in its de-energized state, apower supply circuit for supplying power to said GFCI, said power supplycircuit including means for applying either a first voltage to saidsolenoid or a second voltage to said solenoid, a latch circuit operablein first and second bi-stable states, said latch circuit allowing saidsolenoid to switch from its de-energized state to its energized stateand remain in its energized state when in said first bi-stable state andsaid latch circuit causing said solenoid to switch from its energizedstate to its de-energized state and remain in its de-energized statewhen in said second bi-stable state, and a fault detecting circuit fordetecting the presence of a fault condition in at least one of saidlines extending between the power and the load and for causing saidlatch circuit to latch in its second bi-stable state upon detection ofsaid fault condition.

Additional objects, as well as features and advantages, of the presentinvention will be set forth in part in the description which follows,and in part will be obvious from the description or may be learned bypractice of the invention. In the description, reference is made to theaccompanying drawings which form a part thereof and in which is shown byway of illustration specific embodiments for practicing the invention.These embodiments will be described in sufficient detail to enable thoseskilled in the art to practice the invention, and it is to be understoodthat other embodiments may be utilized and that structural changes maybe made without departing from the scope of the invention. The followingdetailed description is, therefore, not to be taken in a limiting sense,and the scope of the present invention is best defined by the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are hereby incorporated into andconstitute a part of this specification, illustrate various embodimentsof the invention and, together with the description, serve to explainthe principles of the invention. In the drawings wherein like referencenumerals represent like parts:

FIG. 1 is a schematic circuit diagram of a ground fault circuitinterrupter (GFCI) of the present invention; and

FIG. 2 is a schematic diagram of the integrated circuit forming part ofthe circuit of FIG. 1.

DETAILED DESCRIPTION

The following brief definition of terms shall apply throughout theapplication:

The term “comprising” means including but not limited to, and should beinterpreted in the manner it is typically used in the patent context;

The phrases “in one embodiment,” “according, to one embodiment,” and thelike generally mean that the particular feature, structure, orcharacteristic following the phrase may be included in at least oneembodiment of the present invention, and may be included in more thanone embodiment of the present invention (importantly, such phrases donot necessarily refer to the same embodiment);

If the specification describes something as “exemplary” or an “example,”it should be understood that refers to a non-exclusive example; and

If the specification states a component or feature “may,” “can,”“could,” “should,” “preferably,” “possibly,” “typically,” “optionally,”“for example,” or “might” (or other such language) be included or have acharacteristic, that particular component or feature is not required tobe included or to have the characteristic.

Referring now to the drawings and more particularly to FIG. 1, there isshown a ground fault circuit interrupter (hereinafter GFCI) circuitconstructed according to the teachings of the present invention, theGFCI being represented generally by reference numeral 11.

As will be discussed in detail below, GFCI 11 is automatically set toprotect a load from ground fault conditions upon the initial plugging inof the load to a power source. GFCI 11 is also automatically set toprotect the load from ground fault conditions once power is restored tothe power source after a loss of power. Furthermore, once GFCI 11protects the load from a ground fault condition, GFCI 11 can be manuallyreset to protect against further ground fault, conditions.

GFCI 11 includes a circuit breaker 13, a relay circuit 15, a powersupply circuit 17, a booster circuit 19, a fault detection circuit 21, abi-stable electronic latch circuit 23, a filter circuit 25, a tripindicating circuit 10, and a test circuit 27.

Circuit breaker 13 includes a pair of single-pole, double-throw switchesSW1 and SW2 which are located in the line and neutral conductive lines,respectively, between a power source and a load. Circuit breaker 13 actsto selectively open and close the pair of conductive lines. Switches SW1and SW2 can be positioned in either of two connective positions. In thefirst connective position, which is illustrated in FIG. 1, switches SW1and SW2 are positioned such that the power source is not connected tothe load but is connected to booster circuit 19. In the secondconnective position, which is the opposite position illustrated in FIG.1, switches SW1 and SW2 are positioned such that the power source isconnected to the load but not to booster circuit 19. In both positions,the power source is connected to power supply 17.

Relay circuit 15 acts to selectively position switches SW1 and SW2 ineither its first connective position or its second connective position.Relay circuit 15 comprises a solenoid SOL1, a transistor Q1, biasingcircuit comprising resistor R4 and Zener Z1.

Solenoid SOL1 is ganged to the circuit breaker contacts of switches SW1and SW2 and is responsible for selectively controlling the connectiveposition of switches SW1 and SW2. Before power is applied to GFCI 11,solenoid SOL1 positions switches. SW1 and SW2 in their first connectiveposition. When solenoid SOL1 is energized, solenoid SOL1 positionsswitches SW1 and SW2 in their second connective position.

It should be noted that the particular construction of solenoid SOL1 isunique for conventional GFCI devices. In particular, SOL1 issignificantly small in size and requires less power than most solenoidsused in prior art GFCI devices. Specifically, solenoid SOL1 has a coilresistance of 5,000 ohms. As a result of the unique construction ofsolenoid SOL1, line voltage (approximately 120 volts) must be directlysupplied to solenoid SOL1 in order to initially energize solenoid SOL1from its de-energized state. But more importantly, once energized, aconstant voltage of only approximately 28 volts is required to besupplied to solenoid SOL1 in order to keep it in its energized state. Aswill be discussed in detail below, booster circuit 19 is responsible forproviding the line voltage to initially energize solenoid SOL1 from itsde-energized state and power supply circuit 17 is responsible forsupplying the constant voltage of approximately 28 volts to maintainsolenoid SOL1 in its energized state. The reduction in the voltagerequired to maintain solenoid SOL1 in its energized state (approximately92 volts) significantly reduces the power drain of SOL1 in circuit 11and also reduces heat build-up which would minimize solenoid. SOL1useful life.

Transistor Q1 is, for example, an MPSA42 transistor sold by MotorolaCorporation and acts to control the current supplied to energizesolenoid SOL1. When transistor Q1 is off, current cannot flow throughsolenoid SOL1. On the other hand, when transistor Q1 is on, current canflow through solenoid SOL1.

Power supply circuit 17 acts to provide power for GFCI circuit 11. Powersupply circuit 17 comprises a metal oxide varistor MOV1, a siliconrectifiers D7 and D17, voltage dropping resistors R9 and R21, andcapacitor C11. It will be appreciated that capacitor C11 reactancelimits the current flowing though rectifiers D7 and D17.

Varistor MOV1 has a value of 150 volts and acts to protect against avoltage surge from, the AC power source. Silicon rectifiers D7 and D17are preferably IN4007 and act to convert the AC current in the line fromthe power source into a DC current. Voltage dropping resistors R9 andR21 act to limit the constant input voltage supplied to solenoid SOL1for the reasons noted above. Capacitor C11 is shown with a value of 0.47uF but may be any suitable value, and acts to limit the current flowingthough rectifiers D7 and D17 and the constant voltage supplied tosolenoid SOL1. It will be appreciated that an objective of thecapacitive supply circuit arrangement minimizes heat buildup in aconfined space, optimizes relay coil SOL1 energy to substantiallyincrease the relay contact forces, providing for a smaller, more ruggedand higher product performance for the GFCI. Booster circuit 19 acts toprovide a temporary voltage sufficient to initially energize solenoidSOL1 from its de-energized state. Booster circuit 19 comprises a siliconrectifiers D15 and D16 and a surge limit resistor R18. Rectifiers D15and D16 are preferably IN4007 and act to convert the AC power in theline of the power source to DC power. When switch SW1 is in its firstposition and upon the application of power to GFCI 11, rectifiers D15and D16 provide an instant DC voltage to solenoid SOL1 causing solenoidSOL1 to energize which, in turn, causes solenoid SOL1 to move switchesSW1 and SW2 to their second connective position. When switches SW1 andSW2 are moved to their second connective position, booster circuit 19 isdisconnected from the power source. Resistor R18 has a value of 47 ohmsand acts to protect rectifiers D15, D16 and capacitor C11 from overcurrents.

Fault detection circuit 21 acts to detect both ground fault and groundedneutral conditions in the conductive lines when switches SW1 and SW2 arein their second connective position. Fault detection circuit 21comprises a sense transformer T1, a grounded neutral transformer T2, acoupling capacitor C7, a noise suppression capacitor CA, a feedbackresistor R3, a passive ferrite bead FB Chip for RF suppression, and aground fault interrupter chip U1.

Ferrite bead FB Chip helps to prevent unwanted RF noise from beingcoupled into pin 1 of U1, also the inverting input of the Op Ampinternal to U1 (see FIG. 2). As noted earlier RF noise presented to theinverting input of Op Amp (pin 1 of U1) may be amplified sufficiently totrigger one of the comparator amplifiers shown in FIG. 2, therebyoutputting an unwanted SCR trigger signal on pin 5. It will beappreciated that any suitable passive electric component may be used tosuppress unwanted frequency noise.

Transformer T1 is preferably a C-5029-01-00 transformer sold by MagneticMetals and transformer T2 is preferably a F-3006-01 transformer sold byMagnetic Metals. Sense transformer T1 senses the current differentialbetween the line and neutral conductive lines and upon the presence of aground fault condition, transformer T1 induces an associated output fromits secondary windings. Grounded neutral transformer T2 acts inconjunction with transformer. T1 to sense the presence of groundedneutral conditions and, in turn, induce an associated output. Couplingcapacitor C7 has a value of 22 uF and acts to couple the AC signal fromthe secondary winding of transformer T1 to chip U1. Noise suppressioncapacitor CA has a value of 0.47. Capacitor CA acts to prevent faultdetection circuit 21 from operating in response to line disturbancessuch as electrical noise and lower level faults.

Tuning capacitor C3 has a value of 0.033 uF and feedback resistor R3 hasa value of 680 K to 1.5 Mohms. Together capacitor C3 and resistor R3 actto set the minimum fault current at which fault detection circuit 21provides an output signal to latch circuit 23. Interrupter chip U1 ispreferably an FM2145 low power ground fault interrupter circuit. Chip U1serves to amplify the fault signal generated by transformer T1 andprovide an output pulse on pin 5 to activate latch circuit 23.

Latch circuit 23 acts to take the electrical signal produced by faultdetection circuit 21 upon the detection of a ground fault or groundedneutral condition and, in turn, de-energize solenoid SOL1. Latch circuit23 comprises a silicon controlled rectifier SCR1 operable in either aconductive or a non-conductive state, a noise suppression capacitor C2and a reset switch SW4. Rectifier SCR1 is preferably an EC103A rectifierand acts to selectively turn on and off transistor Qi in relay circuit15. Noise suppression capacitor C2 has a value of 2.2 uF and acts inpreventing rectifier SCR1, when in its nonconductive state, from firingas a result of electrical noise in circuit 11. Reset switch SW4 is aconventional push-in type switch and acts when depressed to removeholding current from the anode of rectifier SCR1, causing rectifier SCR1to turn off when it is in its conductive state.

Resistor R2 and capacitor C3 act as a filter circuit to smooth out thevarying DC voltage provided from the power supply and provide a filteredDC voltage to the power input of chip U1. Filter circuit includes avoltage dropping resistor R2 which preferably has a value of 33 K ohmsand acts to regulate the appropriate voltage supplied to chip U1. Filtercircuit also includes a DC filter capacitor C3 which preferably has avalue of 1 uF and acts to filter the ripple of the voltage supplied tochip U1.

Test circuit 27 provides a means of testing whether circuit 11 isfunctioning properly. Test circuit 27 comprises a current limitingresistor R12 having a value of 15 K ohms and a test switch SW3 ofconventional push-in type design. When SW3 is depressed to energize testcircuit 27, resistor. R12 provides a simulated fault current, totransformer T1 which is similar to a ground fault condition.

In use, GFCI 11 functions in the following manner. Prior to initialconnection, switches SW1 and SW2 are normally in their first connectiveposition as shown in FIG. 1.

Upon initial connection of GFCI 11 at one end to the load and at theother end to the power source, line voltage of approximately 120 voltsis applied to solenoid SOL1 through booster circuit 19 and energizessolenoid SOL1. Once solenoid SOL1 is energized, solenoid SOL1 causesswitches SW1 and SW2 to move into their second connective position(opposite the position shown in FIG. 1), thereby eliminating the supplyof power into solenoid SOL1 from booster circuit 19. However, since aconstant 28 volts is supplied to solenoid SOL1 from power supply circuit17, solenoid SOL1 is maintained in its energized state.

With solenoid SOL1 maintained in its energized state rectifier SCR1 isin a nonconductive state and transistor Q1 is on, which enables currentto pass to solenoid SOL1. Upon the detection of a ground fault orgrounded neutral condition, fault detection circuit 21 sends a currentto rectifier SCR1 causing rectifier SCR1 to be in a conductive statewhich, in turn, turns off transistor Q1. With transistor Q1 off, currentdoes not pass through solenoid SOL1 and therefore solenoid SOL1 becomesde-energized. Once de-energized, solenoid SOL1 causes switches SW1 andSW2 to return to its first connective position, thereby cutting offpower from the power source to the load.

Once the fault condition is removed, circuit 11 can be reset by manuallydepressing switch SW4. Depression of switch SW4 causes current to passthrough reset switch SW4 instead of rectifier SCR1, which turns offrectifier SCR1. This, in turn, turns transistor Q1 back on when theswitch SW4 is released which enables solenoid SOL1 to becomere-energized.

With the load plugged into the power source, if there is a loss of powerat the power source, solenoid SOL1 will become de-energized, movingswitches SW1 and SW2 back to their first connective position. When poweris subsequently restored, solenoid SOL1 will become re energized again,which in turn moves switches SW1 and SW2 to their second position.

Indicator circuit LED-C 10 provides a means of visual indication thatthe GFCI is functioning normally and has not tripped in response to aground fault or grounded neutral condition. Indicator circuit LED-Cincludes a silicon rectifier, a light emitting diode LED and a currentlimiting resistor R20. The rectifier is preferably an IN4148 rectifierand acts, to convert the AC power of the line to DC power for diode LED.hi a non-interrupt state line voltage L is rectified by the rectifyingdiode and applied to turn on the LED. If the circuit 11 senses a groundfault condition SOL1 is de-energized; thus turning off LED indicator.

The versions of the present invention described above are intended to bemerely exemplary and those skilled in the art shall be able to makenumerous variations and modifications to it without departing from thespirit of the present invention. All such variations and modificationsare intended to be within the scope of the present invention as definedin the appended claims. For example, it should be noted that theparticular components which make up the aforementioned embodiments maybe interchanged or combined to form additional embodiments.

What is claimed is:
 1. A ground fault circuit interrupter (GFCI) withradio frequency (RF) noise suppression for interrupting the flow ofcurrent through a pair of lines extending between a source of power anda load, said GFCI comprising: a circuit breaker having a switch locatedin one of said lines, said switch having a first position in which thesource of power in its associated line is not connected to the load anda second position in which the source of power in its associated line isconnected to the load; a relay circuit for selectively moving andmaintaining said switch in either said first position or said secondposition, said relay circuit including a solenoid operable in either anenergized state or a de-energized state, said solenoid setting saidswitch in said second position when in its energized state and settingsaid switch in said first position when in its de-energized state, saidsolenoid having a coil resistance of approximately 5,000 ohms; a boostercircuit for selectively supplying a first voltage to the solenoidsufficient to cause said solenoid to switch from its de-energized stateto its energized state, said first voltage being supplied to saidsolenoid through said switch when said switch is in its first position;a power supply circuit, said power supply circuit supplying a secondvoltage to the solenoid, said second voltage being sufficient tomaintain the solenoid in its energized state after being initiallyenergized by the first voltage, the second voltage being less than thefirst voltage, the second voltage being insufficient to switch saidsolenoid from its de-energized state to its energized state; a lightemitting diode circuit for indicating the GFCI is operating normally; alatch circuit operable in first and second bi-stable states, said latchcircuit allowing said solenoid to switch from its de-energized state toits energized state and remain in its energized state when in said firstbi-stable state and said latch circuit causing said solenoid to switchfrom its energized state to its de-energized state and remain in itsde-energized state when in said second bi-stable state; a faultdetecting circuit for detecting the presence of a fault condition in atleast one of said lines extending between the power and the load and forcausing said latch circuit to latch in its second bi-stable state upondetection of said fault condition, wherein the fault detecting circuitcomprises a 26V zener shunt regulator, an OP amp, and a SCR driver; andat least one passive RF noise suppressor for preventing RF noise frombeing amplified by the OP amp and inadvertently triggering the SCRdriver.